Process for obtaining genistin malonate and daidzin malonate

Abstract

Genistin and daidzin malonates are obtained by extracting ground soya bean with methanol or ethanol to obtain an extract. The extract is buffered to a pH of 6 to 9 and then extracted with a water-immiscible solvent. The aqueous phase is recovered, acidified to a pH of 2 to 5.4, and then extracted with a water-immiscible solvent. The organic phase is recovered, neutralized to a pH of 6.8 to 7.2, and the malonates are separated therefrom.

We claim: 
     
       1. A process for obtaining genistin malonate and daidzin malonate comprising: extracting ground soya bean with a solvent selected from the group of solvents consisting of methanol and ethanol to obtain an extract;   buffering the extract with an aqueous buffer solution to obtain an aqueous solution having a pH of from 6 to 9;   extracting the buffered aqueous solution with a water-immiscible organic solvent and recovering an aqueous phase therefrom;   acidifying the recovered aqueous phase to a pH of from 2 to 5.4;   extracting the acidified aqueous phase with a water-immiscible organic solvent and recovering an organic phase therefrom;   neutralizing the recovered organic phase to a pH of from 6.8 to 7.2; and   separating genistin malonate and daidzin malonate from the neutralized organic phase.   
     
     
       2. A process according to claim 1 wherein the neutralized organic phase is dried to obtain an extract containing genistin malonate and daidzin malonate. 
     
     
       3. A process according to claim 2 further comprising passing the extract over a gel column and eluting and collecting a fraction containing genistin malonate and daidzin malonate. 
     
     
       4. A process according to claim 3 further comprising separating genistin malonate and daidzin malonate from each other. 
     
     
       5. A process according to claim 4 wherein genistin malonate and daidzin malonate are separated from each other by subjecting the fraction containing both malonates to inverse-phase chromatography. 
     
     
       6. A process according to claim 5 wherein the fraction containing both genistin malonate and daidzin malonate is passed through a column containing octadecyl silane groups attached to silica and wherein a 10% aqueous ethanol solution is used as eluent at a rate of 2 ml per minute. 
     
     
       7. A process according to claim 1 wherein the ground soya bean has an average particle diameter of from 0.5 mm to 0.8 mm. 
     
     
       8. A process according to claim 1 wherein the ground soya is mixed with a 70%-90% aqueous methanol solution and the mixture is refluxed with stirring for 50-100 minutes at a temperature of 70°-90° C. 
     
     
       9. A process according to claim 8 further comprising filtering the refluxed mixture, recovering a filtrate, and drying the filtrate to obtain the crude extract. 
     
     
       10. A process according to claim 1 wherein the buffered aqueous solution is extracted with a solvent selected from the group of solvents consisting of butanol and ethyl acetate. 
     
     
       11. A process according to claim 1 wherein the recovered aqueous phase is acidified by adding 5-10 N hydrochloric acid. 
     
     
       12. A process according to claim 1 wherein the acidified aqueous phase is extracted with a solvent selected from the group of solvents consisting of butanol and ethyl acetate. 
     
     
       13. A process according to claim 1 wherein each water-immiscible organic solvent is butanol. 
     
     
       14. A process according to claim 1 wherein the ground soya bean is defatted before extraction and separation of the malonates. 
     
     
       15. A process according to claim 14 wherein ground soya beans are mixed with an organic solvent to obtain a mixture, the mixture is refluxed for 50-70 minutes at a temperature of 60°-70° C., the refluxed mixture is cooled and filtered and the ground material is then washed and dried. 
     
     
       16. A method for inhibiting oxidation of a food comprising adding to a food an effective amount of at least one member selected from the group consisting of genistin malonate and daidzin malonate. 
     
     
       17. A method according to claim 16 wherein both genistin malonate and daidzin malonate are added to the food. 
     
     
       18. A method for inhibiting oxidation of a cosmetic comprising adding to a cosmetic an amount of at least one member selected from the group consisting of genistin malonate and daidzin malonate. 
     
     
       19. A method according to claim 18 wherein both genistin malonate and daidzin malonate are added to the cosmetic.